Assessment of Biogas Production Efficiency in Household Waste Anaerobic Digesters

Thesis Abstract

The increasing reliance on renewable energy sources necessitates a comprehensive understanding of household-level biogas systems to optimize their efficiency and contribute to sustainable energy solutions. Despite the growing adoption of household anaerobic digesters (ADs) for organic waste management and biogas production, significant variability exists in their operational performance, primarily driven by factors such as feedstock composition, operational parameters, and design configurations. This study aims to assess the biogas production efficiency of household waste anaerobic digesters, with specific objectives to evaluate the influence of feedstock types and loading rates on biogas yield, identify operational bottlenecks affecting performance, and propose evidence-based optimization strategies to enhance biogas output. Employing a mixed-methodology research design, this empirical study integrates quantitative data collection through systematic field measurements and qualitative insights from participant interviews. The target population comprised 150 households actively operating anaerobic digesters within urban and peri-urban districts. Using stratified random sampling, 60 households (40% of the total population) were selected to ensure representation across different socio-economic groups and digester types. Data collection instruments included calibrated gas flow meters and portable biogas analyzers to measure biogas volume and composition over a six-month period, supplemented by structured interview guides to capture operational practices and maintenance routines. Instrument validity and reliability were ensured through calibration procedures, pilot testing, and adhering to standardized measurement protocols. Quantitative data were analyzed using multiple regression analysis to quantify relationships between input variables (feedstock type, organic loading rate, retention time) and biogas yield, while analysis of variance (ANOVA) examined differences in performance across digester types and operational conditions. Additionally, thematic analysis was employed to interpret qualitative interview data, providing insights into operational challenges and user perceptions. The study draws on the Theory of Planned Behavior to understand household motivations influencing digester management practices. Anticipated findings include a positive correlation between well-balanced feedstock composition and increased biogas production efficiency, with organic loading rates exceeding optimal thresholds leading to diminished returns due to process inhibition. The results are expected to identify key operational bottlenecks such as inconsistent feeding regimes, poor temperature regulation, and substandard digester design components, which collectively impact biogas yield and methane content. The study aims to develop an integrated conceptual model illustrating the interactions between operational variables and biogas productivity, contributing to the existing body of knowledge on decentralized biogas systems. This research will significantly advance understanding of factors influencing biogas efficiency at the household level, informing policymakers, practitioners, and household users on best practices for optimizing biogas systems. The study’s findings will facilitate the formulation of practical guidelines and maintenance protocols tailored to diverse socio-economic contexts, thereby promoting sustainable waste management and renewable energy utilization. The research concludes that targeted interventions in feedstock management and operational training can markedly improve biogas output, ultimately supporting household energy independence and environmental sustainability. Recommendations include the adoption of standardized operation procedures, community-level training programs, and the integration of real-time monitoring sensors for proactive system management. Future research directions suggest expanding the scope to include lifecycle cost-benefit analyses and scaling strategies for wider adoption of efficient household biogas solutions.